Rain forests of the sea??

[Bob Steneck]

Coral folk,

  It's all relative but both rainforests and coral reefs are unique and 
probably worthy of the sound-bite analogy.  Both concentrate diversity, 
have complex habitat architecture and are highly productive (high gross 
productivity).  Species richness and canopy heights are greater in 
rainforests, gross productivity is greater on reefs. Taxonomic 
composition differs significantly.  In rain forests most species are 
insects, angiosperms and birds.  Reefs have no marine insects, hardly any 
angiosperms and certainly no birds.  However, reefs have much greater 
higher-order diversity (e.g., number of phyla).  While there is a wider 
phyletic range of primary producers (endosymbionts, plankton and multiple 
phyla of benthic algae) the within group diversity for each is relatively 
low. For example, species richness in algae is much lower than that for 
angiosperms, reef fish are less diverse than rainforest birds.  There are 
low diversity reefs (e.g., Clipperton in the eastern Pacific, Abrolhos 
off Brazil and Hawaii) that have many of the same zones, groups and 
ecosystem function of high diversity reefs.  I don't know of low 
diversity rainforests - this may reveal my ignorance.

  Coral reefs may be most unique because of their role in producing 
calcium carbonate bioherms (reef rock).  In a relatively short period of 
time, say 500 or 1000 years, they can significantly change their physical 
environment as they grow to and reach sea level.  

  Finally, both ecosystems are globally threatened.  Would it be useful 
to consider the rates of change in these two ecosystems?  Reefs in the 
Caribbean have lost much of their largest framework building corals (the 
acroporids).  Are there rainforest analogs?  Are the two systems equally 
resilient to perturbations?

  Just some food for thought.

Cheers,

Bob Steneck




>Dear Coral List,
>
>        One of Jim Hendee's recent messages reminded me that one of the
>legitimate items for the coral list is "controversial topics in coral
>reef ecology".  
>
>        I am not sure that this is a 'controversial topic', but the
>coral list has been pretty quiet lately.  Are coral reefs really
>analogous to rain forests or is the coral reef community just taking
>advantage of a catchy 'sound bite' to gain status in the eyes of the
>ecologically minded public?
>
>        There are certainly some similarities, but I have often thought
>that the differences are large also.  Anybody care to share their
>thoughts on this topic with the list??
>
>John


-------------------------------
Robert S. Steneck, Ph.D.
Professor, School of Marine Sciences
Pew Fellow in Marine Conservation
University of Maine
Darling Marine Center
Walpole, ME 04573
(207) 563 - 3146 ext. 233 
e-mail:  Steneck at Maine.EDU

The School of Marine Sciences Web site:
http://www.ume.maine.edu/~marine/index.html